Incisional
wounds in rats treated locally with
thymosin beta4 (Tbeta4) healed with minimal scaring and without loss in
wound breaking strength. Treated
wounds were significantly narrower in width. Polarized light microscopy treated
wounds had superior organized
collagen fibers, displaying a red birefringence, which is consistent with mature connective tissue. Control incisions had randomly organized
collagen fibers, displaying green birefringence that is consistent with immature connective tissue. Immunohistology treated
wounds had few myofibroblasts and fibroblasts with alpha smooth muscle actin (SMA) stained stress fibers.
Polyvinyl alcohol sponge implants placed in subcutaneous pockets received either carrier or 100 microg of Tbeta4 on days 2, 3, and 4. On day 14, treated implants revealed longer, thicker
collagen fiber bundles with intense yellow-red birefringence by polarized light microscopy. In controls, fine, thin
collagen fiber bundles were arranged in random arrays with predominantly green birefringence. Controls contained mostly myofibroblasts, while few myofibroblasts appeared in Tbeta4 treated implants. Electron microscopy confirmed both cell types and the degree of
collagen fiber bundle organization. Our results demonstrate that Tbeta4 treated
wounds appear to mature earlier and heal with minimal scaring.